<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>边框的复合写法</title>
    <style>
        div {
            width: 400px;
            height: 190px;
            border-top: 5px solid #000;
            /* 上边框样式 */
            border-bottom: 10px dashed skyblue;
            /* 下边框样式 */
        }
        .one {
            width: 480px;
            height: 160px;
            border: 10px solid skyblue;
            border-top: 10px solid green;
            /* border和border-top不能换顺序，css的层叠性 */
        }
    </style>
</head>
<body>
    <div> <img src="img/边框的复合写法01.png" alt=""></div>
    <div class="one"><img src="img/边框的复合写法02.png" alt=""></div>
</body>
</html>